The Buzz

Migration watch: Monarch butterflies have landed in Illinois

A monarch butterfly rest on the purple flowers of wild bergamot.
(Photo by Anthony Schalk)

Spring is creeping in ever so slowly all around us, and here's another exciting indication that warmer temperatures are right around the corner: Monarch butterflies are winging their way closer to us. The first reported sighting in Illinois came on March 30 in New Berlin, which is just west of Springfield. On the East Coast, they've made it as far north as Rhinebeck, New York.

Thanks to a map from Journey North, you can chart their progress based on reported sightings from citizen scientists.

Historically, the first sightings in Will County come sometime in May.

MonarchMigrationApril2024.jpg

Program coordinator Suzy Lyttle said each year's migration can vary depending on the weather conditions they encounter along their journey. They're much more delicate than birds, she said, and they can't fly in the rain. Winds also can make a big difference. They normally can fly at speeds up to 20 mph, and favorable wind conditions can allow them to travel anywhere from 40 to 100 miles per day.

"From year to year, things change," Lyttle said of their annual trek north. "It just depends. Some years, they're early and some years, they're late."

While we are certain to see monarchs return to Will County, exactly how many varies from year to year as well. The monarchs are heading north from Mexico, and data shows this year's population was the second lowest number on record since monitoring began more than 30 years ago. The butterflies spend the winter in forests, and this year they were only documented in 2.2 acres of forest across multiple Mexican states. This winter's number is down 60% over last winter. For comparison, in the mid-1990s, wintering butterflies were found on approximately 45 acres of forests in Mexico. 

In general, butterfly populations have plummeted in recent decades due to habitat loss, pesticide and herbicide use, and climate change.

You can get involved

Do you want to get in on the reporting action? It's simple and can be accomplished directly through the Journey North site. Just sign up for an account and you're all set. It only takes a minute to share your sighting. The data, which is submitted by more than 60,000 registered users in the U.S., Canada and Mexico, is used to better understand migratory species.

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